Today's distributed online environments use clusters of servers to store and manage everything from e-mail accounts, web searching, online advertising, and numerous other cloud-based functions. Companies providing cloud-scale services need to store and analyze massive data sets, such as search logs and click streams. Mining this data provides valuable insights into software performance, user interactions, and numerous other key information. Programmers analyze the data by submitting backend queries commonly referred to as “jobs” that are executed by backend servers through an online portal.